The present invention relates to a smoking article wrapper composition for significantly reducing ignition proclivity of the smoking article, and a method of making the smoking article wrapper composition. The invention particularly relates to an improved wrapper paper for cigarettes wherein the cigarettes tend to self extinguish if left or dropped on a flammable substrate before igniting the substrate.
There is an ongoing concern in the industry to produce cigarettes having wrappers which reduce the ignition proclivity of the smoking article, in other words the tendency of the smoking article to cause ignition of surfaces which come into contact with the lit smoking article. Reports have been made of fires attributed to burning cigarettes coming into contact with combustible materials. A justifiable interest exists in the industry to reduce the tendency of cigarettes, or other smoking articles, to ignite surfaces and materials used in furniture, bedding, and the like upon contact.
Thus, a desirable feature of smoking articles, particularly cigarettes, is that they self-extinguish upon being dropped or left in a free burning state on combustible materials.
It has long been recognized in the industry that the cigarette wrapper has a significant influence on the smolder characteristics of the cigarette. In this regard, various attempts have been made in the art to alter or modify cigarette wrappers in order to achieve the desired tendency of the cigarette to self extinguish, or to reduce the ignition proclivity characteristics of cigarettes.
For example, it is known in the art to treat bands or other areas of the cigarette paper to reduce the air permeability within the treated areas. It is known from U.S. Pat. No. 4,452,259 to define at least one circumferential band on the wrapper of a smoking article which will hopefully cause the smoking article to extinguish under free burn conditions. The band is formed by applying a liquid substance or compound to the cigarette paper which has a liquid form in a temperature range of about 100.degree. C. to 200.degree. C. This reference teaches that, as the burning cone of the cigarette comes into contact with the band, a film is formed on the cigarette paper as the substance changes to liquid form which substantially restricts the flow of air to the burning coal.
U.S. Pat. No. 4,945,932 teaches another method of providing areas of decreased air permeability which cause the cigarette to self extinguish as the cigarette smolders or burns into the areas of reduced permeability. The '932 patent teaches to form patterned or annular zones in the cigarette paper by multiple batonneing of the paper, for example, by use of an embossing calendar.
U.S. Pat. No. 4,077,414 discloses the use of printed bands of material on cigarette paper to control the burn rate of the cigarette. Although this reference does not particularly address ignition proclivity, it teaches to provide relatively narrow low porosity bands along the cigarette. The bands are formed by applying a gel-forming substance to the paper by painting, printing, or other coating techniques. The reference teaches that preferred gel-forming substances are those which form gels in water, such as gelatin, alginates, methyl cellulose, methylethyl cellulose and gums. Water insoluble substances such as lacquers and varnishes may also be used in an organic solvent.
U.S. Pat. No. 4,889,145 is another reference that teaches providing areas of reduced porosity along the cigarette by applying a discontinuous coating of a porosity reducing composition. This reference is not particularly concerned with ignition proclivity of the smoking article, but with controlling the puff count and tar delivery of the smoking article. This reference also teaches to include a burn promoter in the wrapper to balance the effect of the discontinuous coating areas.
Various other applications and processes for reducing ignition proclivity of a cigarette are known as, for example, by U.S. Pat. No. 4,453,553; U.S. Pat. No. 4,480,650; U.S. Pat. No. 4,739,775; U.S. Pat. No. 4,489,738; U.S. Pat. No. 4,715,345; U.S. Pat. No. 2,666,437; U.S. Pat. No. 4,622,983; and European Patent Application 0 559 300 82.
Although, as set forth in the above identified references, it has been known in the art to attempt to reduce ignition proclivity tendencies of cigarettes by defining discrete areas of reduced porosity or air permeability along the cigarette, the prior art has not provided an economically feasible method of producing such cigarettes on a commercial scale. Cigarettes are produced in relatively high speed commercial processes and any process or system for reducing the permeability of the cigarette paper to control ignition proclivity must be compatible with the high speed cigarette manufacturing process. Thus far, the systems and processes known in the art have been unacceptable in this regard. For example, the known processes are not compatible with conventional high speed printing techniques for applying the porosity reducing solutions to the cigarette wrappers in a high speed commercial operation. Attempts have been made to apply aqueous solutions to the cigarette wrappers, but such attempts have been generally unsuccessful. The aqueous solutions significantly reduce the strength of the paper and also cause the paper to crinkle or pucker in the coated areas. Cigarettes made with these wrappers have a non-uniform and unappealing outer surface.
Thus, what is needed, is a method (and resulting article) for manufacturing a smoking article wrapper wherein a film forming non-aqueous solution is applied to the cigarette paper in discrete areas or bands by way of conventional high speed printing techniques such that a reduced air permeability is achieved in the treated areas which promotes self extinguishing of the cigarette and does not adversely affect taste or quality of the cigarette.